1. Field of the Invention
The present invention relates to a device for detecting a thermally caused linear expansion of a machine element of, for example, a machine tool.
2. Description of the Related Art
Heat is generated in the course of operating a machine tool, for example by the friction of a rotating spindle, which can lead to a thermal expansion of the heated machine element and therefore to inaccuracies of the dimensions of the processed workpiece. If the expansions are known, it is possible to achieve an improved dimensional accuracy of the workpiece by an appropriate readjustment.
DE 38 22 873 C1 describes a device for measuring and adjusting thermally caused linear expansions of machines, in particular machine tools. In the process the electrical resistance of a temperature sensor made of platinum, which is in thermal contact with an area of the machine element, is used as the measurement of the thermal linear expansion of the machine element in this area. Use is made of the fact that the change in the electrical resistance of a metallic conductor, as well as the linear expansion of a machine element, are good approximations of the linear functions of the temperature in a range of approximately 0 to 100° C. Even in case of a temperature distribution along the area of the machine element detected by the temperature sensor, the linear expansion of the machine element then is a good approximation of the linear function of the electrical resistance of the temperature sensor.